CN108145606B - Real-time online monitoring device for large particles of polishing solution in polishing process - Google Patents
Real-time online monitoring device for large particles of polishing solution in polishing process Download PDFInfo
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- CN108145606B CN108145606B CN201711179777.9A CN201711179777A CN108145606B CN 108145606 B CN108145606 B CN 108145606B CN 201711179777 A CN201711179777 A CN 201711179777A CN 108145606 B CN108145606 B CN 108145606B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
- B24B49/12—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving optical means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
- B24B57/02—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents for feeding of fluid, sprayed, pulverised, or liquefied grinding, polishing or lapping agents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/02—Investigating particle size or size distribution
- G01N15/0205—Investigating particle size or size distribution by optical means, e.g. by light scattering, diffraction, holography or imaging
- G01N15/0211—Investigating a scatter or diffraction pattern
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Abstract
The real-time online monitoring device for the large particles of the polishing solution in the polishing process comprises an optical system, a data acquisition and processing system and a system calibration, inspection and auxiliary system, wherein the optical system comprises an observation window, a laser light source, a laser emission light path, a laser attenuation receiving light path and a laser scattering receiving light path, so that photoelectric conversion of large particle light attenuation and light scattering signals in the polishing solution is realized, and the data acquisition and processing system comprises an analog and digital circuit for acquisition and processing of the laser attenuation and laser scattering signals; the calibration and inspection system utilizes standard particle suspension to calibrate a polishing solution large particle detection system, and establishes a relation between laser attenuation and laser scattering electric signals and the known size of standard particles; the auxiliary system includes a sampling system, a cleaning system, and a bubble removal system. The invention has large detection range, real-time online detection, plays an important role in improving the yield of polishing processing with high surface integrity, and reduces the production cost.
Description
Technical Field
The invention belongs to the technical field of particle online monitoring devices, and particularly relates to a real-time online monitoring device for large particles of polishing liquid in a polishing process.
Background
The precise ultra-precise polishing processing can ensure that the processed workpiece has extremely high surface integrity, has ultra-smooth surface with nanoscale roughness, has no damage such as scratches/pits and the like, has extremely low subsurface damage layer, is widely applied to the production process of large-scale integrated circuits, is a necessary processing technology of high-precision parts such as LED sapphire substrates, quartz wafers for laser gyroscopes, blue glass filters for camera modules of smart phones, mute bearing rollers and the like, and plays an important supporting and promoting role in the development of industries such as electronic information, semiconductors, optics, aerospace, weapons and military industry and the like.
The common precise ultra-precise polishing mode is to fill polishing liquid (suspension of nano-scale abrasive particles) on a polishing pad, and the polishing liquid is conveyed to the lower part of a processed surface by the rotary motion of the polishing pad, and the material removal and the processing are realized through the rolling and cutting actions of the abrasive particles. Clearly, the size of the abrasive particles in the polishing liquid has a decisive effect on the surface integrity of the polishing process, and large particles (particles with a larger size than the abrasive particles used) in the polishing liquid are root causes of micro defects such as scratches/pits and the like on the processed surface and limitation of the surface integrity. It has been found that when particles of 1 μm or more are present in the polishing liquid (the abrasive grain size for polishing is usually 30nm to 200 nm), surface defects such as scratches and pits tend to occur on the surface to be processed. At the same time, even at very low levels of the ratio of large particles to abrasive particle count, surface integrity can be significantly affected. The known sources of large particles in polishing solutions are mainly four: the agglomeration of fine abrasive grains (the agglomeration of nano-scale particles is easy to occur due to the large specific surface area and high surface energy), polishing pad abrasive dust, falling objects of a polishing pad trimmer and falling materials generated on the processed surface. It can be seen that the generation of large particles is difficult to avoid and unpredictable. Therefore, the method for monitoring the quantity of large particles in the polishing solution on line in real time and early warning in time is an effective way for ensuring that the processed workpiece has high surface integrity and the yield of mass production is ensured.
At present, polishing equipment used or produced by domestic enterprises does not have a polishing liquid large particle online monitoring system, a passive post detection method is generally adopted, and the improvement of the yield is greatly limited, the production cost is high and the production efficiency is low. Because the polishing process has a considerable degree of randomness and complexity, manufacturers generally adopt empirical process parameters to carry out polishing, and parts are detected and sorted after the polishing process is finished. If the rejection rate caused by surface defects such as scratches, pits and the like is found to be beyond the expected rate in the detection process, the process parameters (the service life of a filter and polishing solution, the period of cleaning equipment and the like) are adjusted. At this time, considerable waste products are often generated, and the polishing is the final machining process of the precise parts, so that the waste products are generated at this time, and the manpower and material investment of each process is meaningless. More seriously, the processing experience is often not very reliable due to unpredictable, controlled generation of large particles, and surface defects often occur in advance unpredictable, resulting in extremely high rejection rates. In actual production, the rejection rate caused by defects such as scratches, pits and the like is up to 30%. On the other hand, the frequent process adjustment not only obviously shortens the service life of consumable materials such as a filter, polishing solution, a polishing pad and the like, but also seriously influences the production efficiency, and further greatly increases the production cost.
Precision polishing has been an important support for the development of the large-scale integrated circuit industry since the successful use of 1991 for 64Mb DRAM production. With the gradual decrease of the line width, micro defects such as scratches generated during polishing become a non-negligible factor in the failure of the device finished product. In order to improve the yield of mass production of large-scale integrated circuits, foreign scholars have conducted a great deal of research and have determined that: (1) Large particles (particles having a size exceeding 1 μm, the average particle diameter of the abrasive particles in the polishing liquid being 0.1 μm) having a size exceeding the abrasive particles in the polishing liquid are the root cause of causing defects such as micro scratches; (2) The main sources of the large particles are agglomeration of fine abrasive particles in the polishing solution, abrasive dust generated by the polishing pad in the cyclic use process of the polishing solution, diamond particles falling off from a polishing pad trimmer and materials generated by the processed surface.
In order to reduce damage of large particles in the polishing liquid to a workpiece to be processed, a part of polishing equipment is provided with a POU (Point of Use) filter in a polishing liquid supply pipeline, and the filter is replaced periodically. Clearly, the filtering effect is affected by the flow rate, concentration, time, etc. of the polishing liquid, and large particles cannot be filtered by one hundred percent (it is reported that a POU filter with a nominal size of 0.5 μm can only filter 80% of particles above 1 μm). More importantly, due to the randomness and complexity of the polishing process, the actual service life of the filter is often shorter than the expected service life due to the influence of some unknown factor, so that the method for periodically replacing the filter is unreliable, and a large number of filters with short service lives are scrapped in advance, so that the waste is huge. In addition, it has been proposed by the scholars to rinse the polishing pad with high pressure deionized water or to suck the polishing pad dry in vacuum while installing the POU filter, further reducing the number of large particles that may occur.
As described above, in view of the complexity and randomness of the polishing process, it is desirable to obtain real-time parameters of the polishing process and to effectively control the process. Currently, real-time monitoring of polishing processes is largely expanding from two aspects. Firstly, a friction force on-line monitoring system is additionally arranged on polishing equipment, and whether large particles enter a processing area or not is judged by detecting the friction force between a polishing pad and a workpiece and the change of friction coefficient in real time, so that micro defects such as scratches and the like appear on the processed surface. Secondly, the particle size distribution in the polishing solution is monitored on line, and early warning is given according to the concentration of large particles in the polishing solution passing through the filter.
On-line particle size analysis instruments for suspensions or particulate matter are of a wide variety, the principles being based on a wide variety of acoustic, optical, electrical, mechanical, and image. The most common particle size measurement method at present is the laser scattering method, which has been developed in the 70 s of the 20 th century, and is classified into two types, static scattering and dynamic scattering. The static scattering uses the angle of scattered light of particles to be related to the size, and the particle size and concentration are calculated by adopting the combination of Fraunhofer diffraction and Mie scattering theory, and the measuring range reaches 0.1 mu m to a plurality of mm. The dynamic scattering method measures particle size from the spectrum of light intensity variation caused by brownian motion of solid particles in suspension, and is applicable to nanoscale particles. Due to brownian motion, the particle scattered light signal intensity is no longer kept constant and fluctuates continuously over time around a certain average value. The smaller the particles, the faster the relief; conversely, the heave is slower. By utilizing the laser dynamic scattering principle, online detection products of the particle size distribution of the polishing solution are developed in 2013 of Malvern corporation, and the detection precision is 0.5nm (the method is limited by the flow rate, the temperature and the concentration and can only detect particles below 1.5 mu m).
The ultrasonic attenuation method obtains the size distribution of particles by measuring the attenuation coefficient of the particle bodies to ultrasonic waves. When an ultrasonic wave propagates in a suspension of ultrafine particles, the existence of scattering and absorption of the ultrasonic wave by the ultrafine particles in the suspension results in the attenuation of sound velocity and acoustic energy of the incident ultrasonic wave during propagation. The attenuation depends on the particle size distribution of the solid particles in the suspension. The ultrasonic wave has the characteristics of strong penetrating power, wide frequency band and non-contact, and can be used for analyzing the particle size of particles between 0.01 and 1000 mu m.
The laser scattering and ultrasonic attenuation method belong to collective detection methods, the signals received at the same time are superposition of response signals generated by all particles, a particle size distribution diagram is obtained after complex mathematical calculation, errors and false marks are inevitably generated in the result due to the defects of calculation, the detection precision is limited, and particularly, the particles are insensitive to large particles with relatively small quantity in a particle set, and the particles have obvious influence on polishing processing quality. The dynamic scattering technique of laser is also limited in that the detection range is too small to detect large particles with insignificant brownian motion in the polishing solution.
Corresponding to the collective detection method is single particle detection, i.e. the signal received by the detector at the same time originates from only a single particle, including light attenuation and focused reflection methods. The light attenuation method is to irradiate the particle flow field with laser light and arrange a photodetector in the right rear. When particles pass through the illumination area, the light intensity received by the detector is attenuated due to the shielding of the particles on the light, the output voltage of the detector is reduced by a degree related to the particle size, and the voltage reduction frequency depends on the particle number. Obviously, the method is only suitable for measuring the condition of low particle concentration, and cannot detect small-size particles due to the limitation of resolution of a photoelectric detector.
The focusing reflection method uses a lens rotating at high speed to make the focusing light beam scan the particle flow field rapidly. When the focused beam impinges on the particle, the beam is scattered, with a portion of the backscattered light entering the detector until the focused beam is removed from the particle. From the time at which the scattered light is received, the chord length of the particle can be calculated, and thus the size of the particle is known. The method has been applied to monitor crystallization processes in the chemical and pharmaceutical industries. This is currently the only way to measure the particle size distribution of high concentrations of particles, but it is obvious that the method does not take into account the mutual occlusion between particles and only local measurements can be made.
Besides the laser dynamic scattering product developed by Malvern, the commercial product for online monitoring of the particle size distribution of the polishing solution also comprises an online monitoring system of the SlurryScope polishing solution, which is proposed by Vantage in 2010, and can measure the particle size distribution of particles between 1.0 and 12.0 mu m. AccuSizer series developed by the company PSS (Particle Sizing Systems) in the United states, the detection range is 0.6-20 mu m, and the resolution is 0.6 mu m. These products are expensive and domestic research in this area is essentially blank.
The laser static scattering and ultrasonic attenuation method is a collective detection method, and can obtain the particle size distribution of particles in the polishing solution, but the detection accuracy is low, and the method is insensitive to a small amount of large particles at the tail part of a particle size distribution curve. The laser focusing reflection method is suitable for detecting large particles of high-concentration polishing liquid, the method does not consider mutual shielding among particles, and when detecting particles with a plurality of microns, the requirement on system hardware is too high. The laser dynamic scattering method is suitable for detecting nanoscale small particles, but the detection range is too small, and large particles with insignificant Brownian motion in polishing solution cannot be detected. The laser attenuation method is suitable for measuring the condition of low particle concentration, is limited by the resolution of a photoelectric detector, and cannot detect small-size particles.
Therefore, the research designs a monitoring device capable of monitoring the size and the number of particles in the polishing solution in real time, provides a reference basis for active and effective control of the polishing process, and has far-reaching application prospect and practical significance.
Disclosure of Invention
In order to overcome the problems and the defects existing in the prior online monitoring of large particles in polishing solution, the invention provides a real-time online monitoring device for large particles, which has a large monitoring range and can realize the effective online monitoring of the large particles in the polishing solution.
In order to achieve the above object, the technical scheme of the present invention is as follows:
the real-time online monitoring device for large particles of polishing liquid in the polishing process comprises an optical system, a data acquisition and processing system, a calibration and inspection system and an auxiliary system; the optical system comprises an observation window, a laser emission light path, a laser attenuation receiving light path and a laser scattering receiving light path, wherein the laser attenuation receiving light path and the laser scattering receiving light path realize photoelectric conversion of large-particle light attenuation and light scattering signals in the polishing solution; the data acquisition and processing system comprises an analog and digital circuit for laser attenuation and acquisition and processing of laser scattering signals; the calibration and inspection system utilizes standard particle suspension to calibrate a polishing solution large particle detection system, establishes a relation between laser attenuation and laser scattering electric signals and the known size of standard particles, and determines the mutual connection of the two detection methods; the auxiliary system includes a sampling system, a cleaning system, and a bubble removal system.
Further, the cleaning system comprises a stirrer, a polishing solution storage tank, a pump, a deionized water pipeline, a polishing solution dilution and mixing system, a filter, a first valve, polishing equipment and a second valve, wherein one end of the pump is connected with the polishing solution storage tank, the stirrer is arranged in the polishing solution storage tank, and the other end of the pump is connected with the polishing solution dilution and mixing system; the polishing solution dilution mixing system is connected with a pipeline for conveying deionized water; one end of the filter is connected with the polishing solution diluting and mixing system, and the other end of the filter is connected with the first valve and the second valve; the first valve is connected with the polishing equipment, and the second valve is connected with an on-line monitoring system.
Still further, the filter includes a screen for filtering foreign substances and a feed/discharge port for adding or removing the polishing liquid, and the temperature of the polishing liquid may be adjusted to 30-60 ℃.
The laser attenuation receiving light path comprises a laser, an achromatic lens, a sample cell, a lens and a transmission light detector, wherein the achromatic lens and the sample cell are sequentially arranged along the propagation direction of a laser beam emitted by the laser, and the laser is vertically incident into the sample cell after being focused by the achromatic lens.
The laser scattering receiving light path comprises a laser, a sample cell, an achromatic lens, a lens and a scattered light detector, wherein the optical axis of the achromatic lens is 45 degrees with the propagation direction of a laser beam emitted by the laser, the achromatic lens is fixed in the direction and receives the scattered light beam from the sample cell, and the optical axis of the achromatic lens coincides with the optical axis of the lens.
Preferably, the laser is a green light source with the wavelength of 532nm, the spot diameter is 2mm, and the output power is 30mW.
The diameter of the achromatic lens is 25.4mm, and the focal length is 50mm.
The sample cell is made of one material of sapphire, optical glass or quartz glass, the sample cell is cuboid, and channels for the polishing solution to circulate are formed in the front end and the rear end of the sample cell.
Preferably, 45 ° is chosen as the scattering angle, the laser is fixed, scattered light is received through the achromat of 25.4mm diameter, and the transmitted signal is received.
Further, the scattered light is received and converged as much as possible on the photosensitive surface of the photodiode by a short focal lens, and the transmitted light passes through the lens, and a photodetection circuit with a lower multiple is used for receiving the signal.
The technical conception of the invention is as follows: and combining laser scattering and a laser attenuation principle, and carrying out real-time on-line monitoring on large particles in the polishing solution. The two methods are combined, so that the method can have the advantages of the two methods, the laser attenuation method is utilized to detect particles with the particle size of more than 1.5 mu m, the laser scattering method is utilized to detect particles with the particle size of 0.6-1.5 mu m, and the method has a relatively wide dynamic particle size range (namely 0.5-20 mu m) on the premise of not losing the great advantage of single particle resolution, thereby meeting the requirement of large particle detection in polishing liquid in the precise ultra-precise polishing process.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the laser scattering method and the laser attenuation method are combined, the defects of a single laser scattering method and a laser attenuation method detection method are overcome, the device has the characteristics of large detection range and real-time online detection, and the device plays an important role in improving the polishing yield of high surface integrity and reducing the production cost. The device can be embedded into a polishing solution supply system, and can realize on-line real-time monitoring on large particles which are generated in the polishing solution due to agglomeration of abrasive particles, falling off of a polishing pad, falling off of a trimmer and the like and can cause micro defects such as scratches and the like.
Drawings
FIG. 1 is an overall schematic diagram of online monitoring of large particles of a polishing solution according to the present invention;
FIG. 2 is a schematic diagram of an optical system of a monitoring device according to the present invention;
FIG. 3 is a schematic view of a light transmission measuring device according to the present invention;
FIG. 4 is a schematic diagram of a light scattering measurement device according to the present invention;
FIG. 5 is a schematic diagram of a mechanism for monitoring large particles of the polishing liquid according to the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
1-5, the real-time online monitoring device for large particles of polishing liquid in the polishing process comprises an optical system, a data acquisition and processing system, a calibration and inspection system and an auxiliary system; the optical system comprises an observation window, a laser emission light path, a laser attenuation receiving light path and a laser scattering receiving light path, wherein the laser attenuation receiving light path and the laser scattering receiving light path realize photoelectric conversion of large-particle light attenuation and light scattering signals in the polishing solution; the data acquisition and processing system comprises an analog and digital circuit for laser attenuation and acquisition and processing of laser scattering signals; the calibration and inspection system utilizes standard particle suspension to calibrate a polishing solution large particle detection system, establishes a relation between laser attenuation and laser scattering electric signals and the known size of standard particles, and determines the mutual connection of the two detection methods; the auxiliary system comprises a sampling system 10, a cleaning system and a bubble removal system 11.
The auxiliary system is connected with the optical system, and the optical system is connected with the system calibration and inspection system and the data acquisition and processing system.
Further, cleaning system includes agitator 1, polishing solution storage jar 2, pump 3, deionized water pipeline 4, polishing solution dilution mixing system 5, filter 6, first valve 7, polishing equipment 8 and second valve 9, place the polishing solution in the polishing solution storage jar 2, there is polishing solution agitator 1 polishing solution storage jar 2 top, and agitator 1 stretches into in the polishing solution storage jar 2, stirs the polishing solution to make the even dispersion of polishing solution. One end of the pump 3 is connected with the polishing solution storage tank 2, and the other end is connected with the polishing solution dilution mixing system 5. The polishing solution diluting and mixing system 5 is connected with a pipeline 4 for conveying deionized water, one end of the filter 6 is connected with the polishing solution diluting and mixing system 5, and the other end of the filter is connected with the first valve 7 and the second valve 9. The first valve 7 is connected with the polishing device 8, and the second valve 9 is connected with an on-line monitoring device.
The polishing liquid is supplied from the polishing liquid storage tank 2, and the polishing liquid in the polishing liquid storage tank 2 is supplied from the pump 3 to the polishing liquid dilution mixing system 5. The polishing liquid in the polishing liquid dilution and mixing system 5 is diluted under the dilution effect of the deionized water, and then impurities are filtered through the filter 6. Between the filter and the polishing apparatus there is a first valve 7. The polishing liquid after the impurities are filtered by the filter 6 is mostly directly supplied to the polishing apparatus 8 through the first valve 7. Between the filter 6 and the auxiliary system there is a second valve 9. Another small part of the polishing liquid after the impurities are filtered by the filter 6 flows into an auxiliary system under the action of the second valve 9.
The filter 6 includes a screen for filtering foreign substances and a feed/discharge port for adding or removing polishing liquid, and the temperature of the polishing liquid may be adjusted to 30-60 ℃.
The auxiliary systems include a sampling system 10, a cleaning system, and a bubble elimination system 11. The polishing solution flowing into the auxiliary system from the second valve 9 is sampled by the sampling system 10, a small amount of polishing solution is extracted by using a vacuum technology for detection, and the deionized water sufficiently dilutes the detection sample. In order to avoid the interference of the air bubbles in the detection sample to the detection result, the air bubble elimination system 11 adopts a vacuumizing method to discharge the air bubbles. The polishing liquid then flows into the cell 12 through a channel in the cell 12, at which point large particle detection is initiated.
The sample cell 12 is made of one material of sapphire, optical glass and quartz glass, and the sample cell 12 is of a rectangular parallelepiped type. The front end and the rear end of the sample cell 12 are provided with channels for circulating the polishing solution.
The laser 13 can emit green light with a wavelength of 532nm, a power of 30mW, and a spot diameter of 2mm. The acromatic lens 17 and the cuvette 12 are arranged in sequence along the propagation direction of the laser beam emitted by the laser 13. The optical axis of the acromatic lens 17 coincides with the optical axis of the laser beam. The achromatic lens 17 has a focal length of 50mm and a diameter of 25.4mm. The laser beam emitted by the laser 13 is focused by an achromatic lens 17 and then is vertically incident to the sample cell 12. When the laser beam passes through the fine particles of the polishing liquid in the sample cell 12, a part of the laser beam is scattered by the polishing liquid particles to deviate from the original propagation direction, and a part of the laser beam is absorbed by the polishing liquid particles, and the laser beam still passes through the medium in the original propagation direction.
Behind the sample cell 12 is the transmission light detector 14, and behind the side of the sample cell 12 is the scatter light detector 15.
Between the cuvette 12 and the transmission light detector 15 there is said lens 18, said lens 18 being a short focal lens. The optical axis of the lens 18 coincides with the optical axis of the acromatic lens 17. After passing through the sample cell 12, the laser beam enters the lens 18, and through the focusing action of the lens 18, the laser beam enters the transmission photodetector 15, and the transmission light is converged on the photosensitive surface of the silicon photodiode of the transmission photodetector 15. The transmitted light detector 15 uses the attenuation characteristics of the light beam to measure the size of the particles, which is related to the ratio of transmitted light intensity to incident light intensity. Since the laser beam emitted by the laser 13 is attenuated after passing through the particulate matter, the size of the particulate matter to be measured can be calculated from the attenuation coefficient according to the lambert-beer law.
Between the cuvette 12 and the scatter detector 14 is the acromatic lens 19 and the lens 20, the acromatic lens 19 having a focal length of 50mm and a diameter of 25.4mm, and the lens 20 being a short focal lens. The optical axis of the acromatic lens 19 is 45 ° to the direction of propagation of the laser beam emitted by the laser 13, in which direction the acromatic lens 19 is fixed, receiving the scattered light beam from the sample cell 12. The optical axis of the acromatic lens 19 coincides with the optical axis of the lens 20. After being focused by the lens 20, the laser beam enters the scattered light detector 14, and the scattered light is converged on the photosensitive surface of the silicon photodiode of the scattered light detector 14. The scattered light detector 14 measures the size of the particles by using the principle that the light beam generates scattering phenomenon after acting with the particles of the polishing solution, and the light intensity of the scattered light is proportional to the particle size of the particles.
The silicon photodiode was Binsonn S1223-02, the PD area of the detector was 3.6x3.6mm, the dark current was 0.1nA, and the junction capacitance was 100pF without bias.
The transmitted light signal and the scattered light signal are converted into electrical signals by the transmitted light detector 15, the scattered light detector 14 and the pre-amplification, and are transmitted to the upper computer for analysis and processing by the a/D sampling. The pre-amplification PD does not employ a bias voltage.
The data acquisition and processing system adopts STC89C52 series single chip microcomputer, and the tri-state data I/O port is used as 8-bit data bus.
The system calibration and inspection firstly utilizes DUKE standard particle suspension (0.5 mu m,1 mu m,2 mu m,5 mu m,10 mu m and 0.5 mu m, 15 mu m mixture) to calibrate the constructed polishing solution large particle basic detection system, and establishes the relation between laser attenuation, laser scattering electric signals and the known sizes of standard particles.
Further, the laser 13 irradiates the sample cell 12, the large particles 21 in the sample cell 12 are measured by the transmission photodetector 15, the small particles 23 in the sample cell 12 are measured by the scattering photodetector 14, the received light signal is converted into a current signal, and the current signal is amplified to generate a voltage (different voltages are generated according to the particle size), and finally a particle size statistical chart is obtained by a computer.
And after the detection is finished, the deionized water is used for fully cleaning the detection loop.
The embodiments described in the present specification are merely examples of implementation forms of the inventive concept, and the scope of protection of the present invention should not be construed as being limited to the specific forms set forth in the embodiments, but also equivalent technical means that can be conceived by those skilled in the art according to the inventive concept.
Claims (4)
1. The utility model provides a polishing solution large granule real-time on-line monitoring device in polishing process which characterized in that: the system comprises an optical system, a data acquisition and processing system, a calibration and inspection system and an auxiliary system; the optical system comprises an observation window, a laser emission light path, a laser attenuation receiving light path and a laser scattering receiving light path, wherein the laser attenuation receiving light path and the laser scattering receiving light path realize photoelectric conversion of large-particle light attenuation and light scattering signals in the polishing solution; the data acquisition and processing system comprises an analog and digital circuit for laser attenuation and acquisition and processing of laser scattering signals; the calibration and inspection system utilizes standard particle suspension to calibrate a polishing solution large particle detection system, establishes a relation between laser attenuation and laser scattering electric signals and the known size of standard particles, and determines the mutual connection of the two detection methods; the auxiliary system comprises a sampling system, a cleaning system and a bubble elimination system;
the cleaning system comprises a stirrer, a polishing solution storage tank, a pump, a deionized water pipeline, a polishing solution dilution and mixing system, a filter, a first valve, polishing equipment and a second valve, wherein one end of the pump is connected with the polishing solution storage tank, the stirrer is arranged in the polishing solution storage tank, and the other end of the pump is connected with the polishing solution dilution and mixing system; the polishing solution dilution mixing system is connected with a pipeline for conveying deionized water; one end of the filter is connected with the polishing solution diluting and mixing system, and the other end of the filter is connected with the first valve and the second valve; the first valve is connected with the polishing equipment, and the second valve is connected with an online monitoring system; the filter comprises a filter screen for filtering impurities and a feed inlet and a feed outlet for adding or taking out polishing liquid, and the temperature of the polishing liquid can be adjusted to 30-60 ℃;
the laser attenuation receiving light path comprises a laser, an achromatic lens, a sample cell, a lens and a transmission light detector, wherein the achromatic lens and the sample cell are sequentially arranged along the propagation direction of a laser beam emitted by the laser, and the laser is vertically incident into the sample cell after being focused by the achromatic lens;
the laser scattering receiving light path comprises a laser, a sample cell, an achromatic lens, a lens and a scattered light detector, wherein the optical axis of the achromatic lens is 45 degrees with the propagation direction of a laser beam emitted by the laser, the achromatic lens is fixed in the direction and receives the scattered light beam from the sample cell, and the optical axis of the achromatic lens coincides with the optical axis of the lens.
2. The device for real-time online monitoring of large particles of polishing liquid in a polishing process as claimed in claim 1, wherein: the laser is a green light source with the wavelength of 532nm, the spot diameter is 2mm, and the output power is 30mW.
3. The device for real-time online monitoring of large particles of polishing liquid in a polishing process as claimed in claim 1, wherein: the diameter of the achromatic lens is 25.4mm, and the focal length is 50mm.
4. The device for real-time online monitoring of large particles of polishing liquid in a polishing process as claimed in claim 1, wherein: the sample cell is made of one material of sapphire, optical glass or quartz glass, the sample cell is cuboid, and channels for the polishing solution to circulate are formed in the front end and the rear end of the sample cell.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711179777.9A CN108145606B (en) | 2017-11-23 | 2017-11-23 | Real-time online monitoring device for large particles of polishing solution in polishing process |
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| CN113103150A (en) * | 2021-04-23 | 2021-07-13 | 长鑫存储技术有限公司 | Polishing liquid supply system, polishing apparatus, exhaust method, and polishing method |
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| CN113552048A (en) * | 2021-07-26 | 2021-10-26 | 苏州苏信环境科技有限公司 | Particle counting method |
| CN113552050A (en) * | 2021-07-26 | 2021-10-26 | 苏州苏信环境科技有限公司 | Working method of particle counter |
| CN113552049A (en) * | 2021-07-26 | 2021-10-26 | 苏州苏信环境科技有限公司 | Working method of particle counter |
| CN113552045A (en) * | 2021-07-26 | 2021-10-26 | 苏州苏信环境科技有限公司 | Calibration method and working method of particle counter |
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